Human Sensory Reception

7/28/2019 Human Sensory Reception

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Human SensoryReception


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Sensory receptor = monitors the external &

internal environment by responding to selectedstimuli, then translating those stimuli into nerve

impulses

Types

1. Chemoreception

2. Mechanoreception

3. Photoreception


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Sensory Organs

General sensory organs = widely distributed over

the surface and interior of the body

1. General Somatic Receptors

2. General Viscera Receptors

Special Sensory Organs

1. confined to the head


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A. Touch Localization

Touch localization

ability to distinguish which area of the body atactile stimulus was applied to

affected by tactile receptors

Touch discrimination

ability to discern two points of tactile stimuli at thesame time

affected by: (1) Receptor density

(2) Sizes of receptive fields


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Somatosensory System for sensory modalities

Mechanoreceptors contact and movement

Meissners corpuscles - light touch

Bulbous corpuscles - tension deep in skin

Merkel nerve endings - sustained pressure

Lamellar corpuscles - rapid vibration


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Meissners Corpuscles

Phasic (rapidly adapting)

Action potential from the change in shape

Superficial location


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Body Part Ave. Error of

Localization

(Subject 1)

Ave. Error of

Localization

(Subject 2)

Back of hand 9.34 10

Neck area 22.34 4.67

Fingertips 5 8.67


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B. Sound Localization

Location of sound

source

Response of Subject 1 Response of Subject 2

Mid-dorsal Behind (dorsal) In front (ventral)

Mid-ventral Behind (dorsal) In front (ventral)

Beside right ear Slightly behind right To the right

Beside left ear Slightly behind left To the left

Between mid-dorsal

and right ear

Between mid-dorsal

and right ear

Between mid-ventral

and right-ear

Between mid-dorsal

and left ear

In general direction Varied, but in general

direction

Directly above head Above head To the front

Directly under chin In front of face Under the chin


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Sound localization ability to discern location of

the source of sound

Auditory space surrounds the observer, exists

wherever there is sound

Coordinates in space:

Azimuth

ElevationDistance


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Generally:

Most accurate: in front

Least accurate: to the sides and from behind

Location cues are calculated


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Binaural cues comparison of signals

received by both ears

Interaural time difference (ITD) - difference

between the amount of time sounds reach the twoears

ITD approx. range: 0 for a sound straight ahead to

about 690 s for a sound at 90 azimuth (directly

opposite one ear)

Medial superior olives


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Interaural level difference (ILD)- difference in

sound pressure intensity (level) received

Sounds are more intense at the ear closer to the

source

Maximum: 90, -90; Minimum: at 0 and 180

High frequency sounds reduce intensity received by

farther ear

Acoustic shadow

Lateral superior olives


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Jeffress Model

Neurons receive signals from both ears

Coincidence detectors

Ear impairment


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C. The Blind Spot

RESULTS

Subject Recorded Distance

for Right Eye (cm)

Recorded Distance

for Left Eye (cm)

1 40 37

2 38 33

3 40 37

Table ?. Recorded distances for the right and left eyes for the Blind Spot Test.


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C. The Blind Spot

Blind spot area on the retina

Where optic nerve enters

No rods and cones


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C. The Blind Spot

Each eye has adifferent visual field

Brain fills in the

gaps


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C. The Blind Spot

Fovea centralis

Center of maula

lutea

Area of highest

acuity of vision

1.5 mm in diameter

Densely-packedcone cells


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C. The Blind Spot

Blind spot 15degrees from

the fovea

centralis, on the

nasal side


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C. The Blind Spot

s = 2d / D

s = diameter of blind

spot

d = size of blind spot

image on card

D = distance fromeye to card


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D. Negative After Images:

Complimentary ColorsRESULTS

What was perceived:

The figures (triangle and circle) were in the same

position.

The triangle was brighter, seemingly glowing.

The circle was slightly darker.


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Complimentary ColorsAfter image

Optical illusion

Brief exposures to intense stimuli

Otherwise dark conditions

Prolonged exposure

Well-lighted conditions


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Complimentary ColorsPositive After Image

Retention of original colors


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Complimentary Colors

Negative After Image

Colors are inverted


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Complimentary ColorsTrichromatic Theory

Thomas Young and Hermann von Helmholtz

Three types of cone receptors


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Opponent Process

Theory

Ewald Hering: somecolor combinations we

never see

Color perception

controlled by twoopponent systems

Blue-yellow

mechanism

Red-green

mechanism


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Complimentary ColorsAnomalous

trichromatism

Protoanomaly

DeuteranomalyTritanomaly

Anomalous

dichromatism

Protanopia

Deuteranopia

Tritanopia

Monochromatism

Achromatopsia


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E. Labyrinthine Reflexes

Subjects sits

on the

rotating chair.

Chair is rotated

15 times with a

speed of one

rotation per 2sec.

The eye

movement of the

subject is

observed

Subjectstands up

and walks.


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Visual and vestibular system responsible in

maintaining visual clarity during head

movements.

Vestibulo-ocular reflex - moves the eye oppositeto head movement in order to stabilize vision.


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Stimulation of lateral semi-circular canals =

head bent forward 30, right rotation.

Rotary Feeling: spinning to the right

Rotatory Nystagmus (not seen because

subject is spinning, eyes closed): fast-right,slow-left (pursuit)

Postrotatory Feeling: spinning to the left

Postrotatory Nystagmus: (seen after spinning

stops and subject opens eyes): fast-left, slow-right (saccade)

Postrotatory Compensation: Subject leans to

the right


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Stimulation of superior semi-circular canals =

head on right shoulder, right rotation.

Rotatory Feeling: falling backward

Rotatory Nystagmus (not seen because

subject is spinning, eyes closed): fast-up,slow-down

Postrotatory Feeling: falling forward

Postrotatory Nystagmus: (seen after spinning

stops and subject opens eyes) Fast-down,slow-up

Postrotatory Compensation: Subject leans to

back


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Static Equilibrium

maintain stability and posture when the head and

body are not moving


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F. Proprioception and Spatial

Orientation

Proprioception balance, coordination, agility

Proprioceptors sensors in the muscles and

tendons that help govern your balance.


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The Spinocerebellar Tract


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Cues in Keeping Spatial Balance

Proprioceptionposition of ones body parts

Equilibrioception vestibular sense. determines

if body is in stable equilibrium or balance.

Exteroreception positions of the body, distance

from objects, and rate of movements. involves

visual mechanism.


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References

Amin, M. (2012). Vestibulooclear Reflex Testing. Retrieved fromhttp://emedicine.medscape.com/article/1836134-overview

Cherry, K. (n.d.). Retrieved from http://psychology.about.com

Gurney, Peter. Our Eye Movement and Their Control: Part 2. [Online].

Answersingenesis.org.http://www.answersingenesis.org/articles/tj/v17/n1/eye. [April 1, 2003]

Herbert, T. (2008). Vision. Retrieved fromhttp://www.bio.miami.edu/tom/courses/bil265

Pastorino, E. & Dolye-Portillo, S. (2010). What is Pscyhology?Essentials.

Yin, T. (n.d.) The Jeffress Model. Neurophys.wisc.edu.
http://emedicine.medscape.com/article/1836134-overviewhttp://psychology.about.com/http://www.answersingenesis.org/articles/tj/v17/n1/eyehttp://www.answersingenesis.org/articles/tj/v17/n1/eyehttp://psychology.about.com/http://emedicine.medscape.com/article/1836134-overviewhttp://emedicine.medscape.com/article/1836134-overviewhttp://emedicine.medscape.com/article/1836134-overview

Human Sensory Reception

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